Three police officers were taken to hospital after breathing in toxic fumes from the spill from chemicals in a crashed truck and trailer unit.
The truck carrying acids and pool cleaner crashed on SH1 near Karapiro, between Cambridge and Tirau, at 11.30pm yesterday, and a cocktail of chemicals from the freight created dangerous chlorine gas.
The three officers had been on the scene for some time when they began to feel unwell and were taken to hospital as a precaution.
Fire Service northern communications manager Jaron Phillips said 30 firefighters attended the scene with seven appliances including the hazardous response unit which has come from Hamilton.
A cordon was put in place on the highway 8km north of the crash site as fire crews worked through the night to clear the contamination.
The Fire Service said all crew were wearing protective clothing and decontamination showers were in place.
By late morning the spill was cleared and the road reopened.
